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| United States Patent |
5,743,975
|
|
Sinopoli
, et al.
|
April 28, 1998
|
Radial medium truck tire with organic polymer reinforced top belt or
breaker
Abstract
A radial medium truck (RMT) tire has belt or breaker plies which are
reinforced by organic reinforcement cords or filaments. In one embodiment,
organic monofilaments are used in the belt or breaker plies which have the
following characteristics: at least 2,000 denier (2,200 dTex), a tenacity
of at least 3.5 g/denier (31 cN/TeX), an initial modulus of at least 30
g/denier (265 cN/Tex) and a shrinkage of at most 6%.
| Inventors:
|
Sinopoli; Italo M. (Canton, OH);
Morgan; John Gomer (North Canton, OH);
Hardy; Anthony (Bettendorf, LU);
Susutoglu; Murat Yasar (Bissen, LU)
|
| Assignee:
|
The Goodyear Tire & Rubber Company (Akron, OH)
|
| Appl. No.:
|
427524 |
| Filed:
|
March 24, 1995 |
| Current U.S. Class: |
152/527; 152/451; 152/526; 152/531; 152/532; 152/534; 152/536; 152/556; 152/565 |
| Intern'l Class: |
B60C 009/00; B60C 009/08; B60C 009/18; B60C 009/20 |
| Field of Search: |
152/527,531,451,533,536,534-535,556,532,565,526
156/95-96
|
References Cited
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| |
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| 3757843 | Sep., 1973 | Carr.
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| 3785423 | Jan., 1974 | de Carbon.
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| 3850219 | Nov., 1974 | Snyder.
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| 3851693 | Dec., 1974 | Takemura et al.
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| 3874436 | Apr., 1975 | Hashida et al.
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| 3982580 | Sep., 1976 | Inoue et al.
| |
| 3990493 | Nov., 1976 | Caretta.
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| 4029137 | Jun., 1977 | Suydam.
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| 4077454 | Mar., 1978 | Miyoshi et al.
| |
| 4140168 | Feb., 1979 | Caretta.
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| 4146415 | Mar., 1979 | Caretta et al. | 152/536.
|
| 4176703 | Dec., 1979 | Nojima et al.
| |
| 4284117 | Aug., 1981 | Poque et al.
| |
| 4286644 | Sep., 1981 | Pond, Jr.
| |
| 4371025 | Feb., 1983 | Canevari et al. | 152/536.
|
| 4498514 | Feb., 1985 | Maathuis et al.
| |
| 4724881 | Feb., 1988 | Poque et al. | 152/527.
|
| 4779660 | Oct., 1988 | Tsuranaga.
| |
| 4850412 | Jul., 1989 | Gupta.
| |
| 5027877 | Jul., 1991 | Tamura et al.
| |
| 5032198 | Jul., 1991 | Kojima et al. | 152/531.
|
| 5082713 | Jan., 1992 | Gifford | 152/527.
|
| 5111864 | May., 1992 | Nakano et al.
| |
| 5365988 | Nov., 1994 | Soderberg et al.
| |
| 5427176 | Jun., 1995 | Hayashi et al. | 152/536.
|
| Foreign Patent Documents |
| 265074 | Oct., 1963 | AU | 152/527.
|
| 2052094 | Mar., 1992 | CA | 152/536.
|
| 0350944 | Jan., 1990 | EP.
| |
| 0356159 | Feb., 1990 | EP.
| |
| 0396494 | Nov., 1990 | EP | 152/527.
|
| 0407071 | Jan., 1991 | EP.
| |
| 0420333 | Apr., 1991 | EP.
| |
| 0448901 | Oct., 1991 | EP.
| |
| 0477771 | Apr., 1992 | EP.
| |
| 0605177 | Jul., 1994 | EP.
| |
| 1137731 | Jun., 1957 | FR | 152/527.
|
| 1313763 | Nov., 1962 | FR | 152/527.
|
| 1495730 | Aug., 1967 | FR | 152/527.
|
| 1943407 | May., 1970 | DE.
| |
| 2185805 | Jul., 1990 | JP | 152/531.
|
| 2179504 | Jul., 1990 | JP | 152/531.
|
| 3-79402 | Apr., 1991 | JP | 152/527.
|
| 4-46804 | Feb., 1992 | JP | 152/536.
|
| 4-46803 | Feb., 1992 | JP | 152/536.
|
| 4-38205 | Mar., 1992 | JP | 152/527.
|
| 4-66305 | Mar., 1992 | JP | 152/527.
|
| 4328002 | Nov., 1992 | JP | 152/527.
|
| 5-8610 | Jan., 1993 | JP | 152/533.
|
| 5286308 | Nov., 1993 | JP | 152/527.
|
| 6-24205 | Feb., 1994 | JP | 152/527.
|
Other References
"Treating Tire Fabrics of Hyten", DuPont Company Textile Fibers Department,
Wilmington, DE, Oct. 1989.
Research Disclosure Apr. 1989, 30076, "Polyamide Monofilament", E.I. duPont
de Nemours & Co., Inc.
"Hyten.TM. Saves Weight in Tires", DuPont Company Textile Fibers
Department, Wilmington, DE, Jun. 1989.
Product Licensing Index, "P-20 Monofil for Tire Reinforcement", EI, DuPont
de Nemours & Co., Inc., 1972, No. 9610.
Mechanics of Pneumatic Tires, ed Samuel Clark: U.S. Dept of Transportation,
Aug., 1981, p. 131.
|
Primary Examiner: Johnstone; Adrienne C.
Attorney, Agent or Firm: Wheeler; David E.
Claims
What is claimed is:
1. A pneumatic radial medium truck tire comprising at least a pair of
parallel annular beads, at least one carcass ply wrapped around said beads
only four belts or breakers consisting of three belts reinforced with
steel filaments or cords at an angle of 12 to 35 degrees with respect to
the equatorial plane (EP) of the tire and a top belt reinforced with nylon
monofilaments disposed over said at least one carcass ply at an angle of 0
to 35 degrees with respect to the equatorial plane of the tire in a crown
area of said tire, a tread disposed over said four belts and sidewalls
disposed between said tread and beads, wherein said nylon monofilaments
are obround in cross section and coated with a resorcinol formaldehyde
latex (RFL) adhesive are 6,000 denier (6,700 dTex) and have a tenacity of
at least 3.5 g/denier (31 cN/Tex), an initial modulus of at least 30
g/denier (265 cN/tex), and an elongation at break of at least 17% and a
shrinkage of at most 6%, and wherein said nylon monofilaments have an
angle with respect to the equatorial plane (EP) of the tire which is
substantially the same as the angle of the steel filaments of cords of the
adjacent belt radially inward of said top belt.
2. The tire of claim 1 wherein the axial edges of the top belt extend
axially beyond the axial edges of the steel belts.
3. The tire of claim 1 wherein the nylon of said nylon monofilaments is
nylon 66.
4. The tire of claim 1 wherein said nylon monofilaments in the top belt
have a concentration of 8 to 16 ends per inch and said steel filaments or
cords in the three steel belts have a concentration of 9 to 16 ends per
inch.
Description
BACKGROUND OF THE INVENTION
The present invention relates to radial truck tires, preferably radial
medium truck (RMT) pneumatic tires.
The treads of RMT tires are subject to puncture from stones and other sharp
objects in the road surface. In many cases, although the puncture is not
deep enough to penetrate the belt package and destroy the tire, it is deep
enough to expose the steel reinforcement cords of the belt package to
water and air, and such exposure can cause the belt package to corrode.
This problem is aggravated when tires are used in mixed service, i.e.,
partially on paved surfaces and partially on non-paved surfaces, such as
exist on the Alaska Highway. Although rust does not significantly affect
the strength of the reinforcement ply, many tires are scrapped if
excessive corrosion is observed on the top belt when the tread is skived
from the tire in preparation for retreading.
In the conception of the present invention, it was proposed to replace some
of the steel reinforced belts in the belt package, and at least the top
belt, with a non-corrosive belt made with organic reinforcement, or to add
such a belt to the top of the belt package. It was decided to test large
diameter, obround nylon 66 monofilaments for such purpose. Monofilaments
of similar structure have been used in radial ply tires as described in
U.S. Pat. 4,850,412 issued to Gupta, Jul. 25, 1989.
SUMMARY OF THE INVENTION
A pneumatic radial medium truck tire of the invention comprises at least
one pair of parallel annular beads, at least one carcass ply wrapped
around said beads, two to twelve belts or breakers disposed over the
carcass ply in a crown area of the tire, a tread disposed over the belts
or breakers, and sidewalls disposed between the tread and the beads. The
majority of the belts or breakers in the tire are reinforced with steel
filaments or cords, and the remaining belts or breakers are reinforced
with organic polymer filaments or cords. The top belt or breaker is
reinforced with organic polymer filaments or cords.
In an illustrated embodiment, the organic filaments or cords are nylon
monofilaments which have an obround (oblong) cross section and are at
least 2000 denier (2200 dTex) and have a tenacity of at least 3.5 g/denier
(31 cN/Tex), an initial modulus of at least 30 g/denier (265 cN/Tex), an
elongation at break of at least 17% and a shrinkage of at most 6%.
In various embodiments of the invention, the top belt or breaker ply is a
nylon monofilament reinforced ply wherein the reinforcement cords have an
angle of 0.degree. to 35.degree. with respect to the equational plane (EP)
to the of the tire. In some such constructions, an organic monofilament
reinforced ply is used as an overlay/top breaker wherein the ply extends
beyond the edges of the other breakers, and the angle of the reinforcing
cords are maintained at substantially the same angle as the steel
reinforcement cords in the breaker ply next radially below, or are at
angles which cross said steel reinforcement cords.
Specific constructions of such tires are also claimed. It is an object of
this invention to reduce corrosion of RMT tires caused by penetration of
the tread by sharp objects, and therefore improve their retreadability.
Other objects of this invention will be apparent from the following
description and claims.-.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a tire according to one embodiment of
the invention taken in a plane that contains the axis of rotation of the
tire.
FIG. 2 illustrates a portion of a reinforcing ply using obround reinforcing
monofilaments.
FIG. 3 is an enlarged cross-sectional view of an obround monofilament cord
suitable for use in the present invention.
FIG. 4 is an enlarged cross-sectional view of an alternative monofilament
cord with rounded edges.
FIG. 5 is an enlarged cross sectional view of a crimped or flattened
monofilament cord.
FIG. 6 is a cross sectional view of an alternative embodiment of a tire of
the invention.
FIG. 7 is a cross sectional view of another alternative embodiment of a
tire of the invention.
DEFINITIONS
As used herein and in the claims, the terms
"obround" refers to a cross sectional shape having a width greater than its
height and having no sharp corners (e.g. oval), and generically is
intended to include similar rounded shapes,
"axial" and "axially" refer to directions which are parallel to the axis of
rotation of a tire,
"radial" and "radially" refer to directions that are perpendicular to the
axis of rotation of a tire,
"bead" refers to that part of a tire comprising an annular tensile member
wrapped by ply cords and shaped, with or without other reinforcement
elements to fit a designed tire rim,
"carcass" refers to the tire structure apart from the belt structure,
tread, undertread, and sidewall rubber but including the beads, (carcass
plies are wrapped around the beads),
"equatorial plane (EP)" refers to a plane that is perpendicular to the axis
of rotation of a tire and passes through the center of the tire's tread,
"belt" or "belt ply" refers to an annular layer or ply of parallel cords,
woven or unwoven, underlying the tread, not anchored to the bead, and
having cord angles of from 12.degree. to 35.degree. with respect to the EP
of the tire,
"breaker plies" refers to annular reinforcement members in the crown area
of a bias ply tire having longitudinal reinforcement members having an
angle (in the illustrated embodiment) with respect to the equatorial plane
of the tire of about 5.degree. less than the angle of such reinforcement
members in the bias carcass plies,
"crown" refers to substantially the outer circumference of a tire where the
tread is disposed,
"rivet" refers to the amount of space between two adjacent cords,
"tenacity" refers to breaking stress expressed as force per unit linear
density of an unstrained specimen (cN/Tex or gm/denier), (usually used in
textiles),
"modulus" refers to the ratio of the change in stress to the change in
strain, and
"organic" refers to compounds, including polymers, containing a carbon
backbone or structure, which can be shaped, stretched of formed into a
particular physical configuration.
DETAILED DESCRIPTION OF THE INVENTION
With reference now to FIG. 1, a preferred embodiment of a pneumatic tire 10
is illustrated which comprises a pair of substantially parallel annular
beads 15, carcass ply 16 wrapped around the beads, belts or breakers 22
comprising three steel cord reinforced plies 12 and one organic polymer
reinforced ply 14 disposed over the carcass ply 16 in a crown portion 24
of the tire, tread 28 disposed over the belts or breakers, and sidewalls
26 disposed between the tread and the beads.
The carcass plies and breaker plies, as is common in the art, are
reinforced with substantially parallel longitudinal reinforcing members.
The present invention relates specifically to pneumatic tires which have
belts or breaker lies which are at least partially reinforced by organic
cords or filaments. Any organic material, having sufficient strength and
durability for the purpose described, can be used in the invention.
Examples of such materials are thermoplastics such as nylon 46, nylon 66,
nylon 6, and nylon 12; polyesters such as polyethyleneterephthalate (PET),
and polyethylenenapthalate (PEN); and polyvinyl alcohol (PVA).
In the illustrated embodiment, longitudinal reinforcing cords comprising
nylon monofilaments have been used. The nylon monofilaments used in the
belts or breaker plies have an obround (oblong) cross section (flat) and
are at least 2000 denier (2200 dTex) and have a tenacity of at least 3.5
g/denier (31 cN/Tex), an initial modulus of at least 30 g/denier (265
cN/Tex), preferably at least 40 g/denier (353 cN/Tex), an elongation at
break of at least 17% and a shrinkage of at most 6%. Although laboratory
data has suggested that reinforcing composites made using such organic
reinforcement do not have adequate penetration resistance for the intended
purpose, experiments utilizing such reinforcement plies in tires have
shown that such monofilament reinforcing cords have good penetration
resistance in the environment of a tire, and initial road testing has
shown that corrosion in tires using top belt plies reinforced by such
monofilaments has been greatly reduced, and the ease of retread
preparation has been greatly increased.
With reference to FIG. 2, monofilaments 11 may be held in relationship to
one another by pick filaments 13 to form fabric 20 for their incorporation
in an elastomeric material to form a ply.
Those skilled in the art will recognize that materials having greater
strength and elongation properties could improve the performance of any
tire made therewith. It is believed that the above data, together with
resistance to chemicals, heat and humidity, represents the minimum
physical requirements of a monofilament reinforcement material used to
make tires in accordance with the present invention.
The maximum tenacity for this type of material is estimated to be about 10
g/denier (89 cN/tex), the maximum initial modulus is estimated to be about
70 g/denier (620 cN/tex), and the maximum elongation at break is estimated
to be about 22%.
Monofilaments of nylon, particularly well suited for implementing the
invention are those sold by E.I. Dupont de Nemours & Co. of Wilmington,
Del. under the Trademark "HYTEN".
In the tire 10 of the invention, the carcass ply is wrapped over beads 15
such that reinforcement cords have an angle of between about 10.degree.
and 90.degree., preferably about 90.degree. with respect to the equatorial
plane of the tire. By definition, the reinforcement members in belt or
breaker plies have an angle at least 5.degree. less than the angle of the
reinforcement members in the carcass plies, and accordingly, the
reinforcement members in the belt or breaker plies have an angle of
between about 5.degree. and 35.degree. preferably about 22.degree., with
respect to the equatorial plane of the tire.
With reference now to FIGS. 3, 4 and 5, cross sections of nylon
monofilaments particularly suited for practicing the invention are
illustrated. Round filaments, slightly flattened filaments with a
substantially oval section (See FIG. 3), strongly flattened filaments with
rounded off edges (see FIG. 4) or filaments having a central constriction
(See FIG. 5), can be used. Preferably, the nylon monofilaments should have
their greatest linear cross-sectional extent, i.e., their width, one to
five times the linear cross-sectional extent perpendicular to said width,
i.e., their thickness. In order to improve the adhesion of rubber to the
filaments, profiled, serrated filaments, or filaments with a multi-lobal
shaped cross-section can be of advantage. It may also be of advantage in
practicing the invention to coat the filaments with a suitable adhesive,
for example a conventional RFL adhesive, or to otherwise treat the
filaments to promote adherence of rubber to the monofilaments.
The organic textile reinforcing elements used in the top belt or breaker
ply can each comprise a monofilament of at least 2,000 denier (2,200
dTex), for example 2,000 denier to 9,000 denier (10,000 dTex), preferably
between about 4,000 and 6,000 denier (4,400 and 6,700 dTex) nylon. A
monofilament is by definition a cord consisting of one filament. When
using monofilaments of 4000 denier and up, the monofilaments in each ply
are disposed with a density of about 8 to 16 EPI (ends per inch),
preferably 10 to 15 EPI in order to yield the desired mechanical
characteristics of the tire.
Tires have been manufactured according to a preferred embodiment using
obround 6,700 dTex (6,000 denier) nylon monofilaments having the following
approximate characteristics:
section height: 0.47 mm
section width: 1.45 mm
tenacity: 81.5 cN/Tex (9.2 g/denier)
lase: 202 N @7% elongation
elongation at break: 19%
shrinkage: 3.7%
The different strength measurements were made using a standard tensile
tester, and the shrinkage measurement was made using a Testrite shrinkage
tester. Tires made using plies having nylon 66 monofilament reinforcing
members demonstrate increased tire endurance and durability.
In illustrated embodiments of the invention, RMT tires have been made
wherein the conventional construction has been changed by removing the top
steel reinforced belt ply and replacing it with one nylon monofilament
reinforced ply 14 over three steel reinforced belt plies 12(in a first
embodiment) (see FIG. 1), and two nylon monofilament reinforced plies
14replace one steel reinforced belt ply (in a second embodiment) (see FIG.
6).
The end count for the steel reinforced plies may vary from 9 to 16 epi, and
in the illustrated embodiments, the end count is 12 to 14 epi.
In one illustrated embodiment, one ply having 9,000 denier (10,000 dtex)
obround nylon 66 reinforcement was used at 12.5 epi. In an alternative
embodiment, two plies of 6,000 denier (6,700 dtex) obround nylon
reinforcement were used at 15 epi.
Also, tires have been made using a conventional construction where an
additional nylon monofilament reinforced belt ply (having an angle of
0.degree. to 35.degree. with respect to the EP of the tire) has been added
to the top of the belt package (see FIG. 7). In one illustrated
embodiment, tires have been made wherein an organic monofilament
reinforced ply has been used as an overlay/op breaker wherein the ply
extends beyond the edges of the other breakers, and the angle of the
reinforcing cords are maintained at the same angle as the steel
reinforcement cord in the breaker ply next radially below. By applying the
top ply wherein the cords have the same angle as the reinforcement cord in
the ply below, a less stiff belt package, that has improved flexibility
and enveloping properties, is provided.
It may be possible to further improve the characteristics of such a belt
package by positioning an optional thick cushion compound 17 (see FIG. 1)
between the top breaker and the next breaker radially below.
Those skilled in the art will recognize that other steel reinforced belts
in the belt package may be replaced by plies reinforced with nylon
reinforcement cords, it being most important to the present invention,
with an object to prevent corrosion in RMT tires subjected to severe use,
that the top belt in the belt package is an organic reinforced ply.
It has been found that tires made according to the invention have improved
retreadability because the damage to the top breaker is reduced. The time
required for the buzz out operation (the grinding away of damaged spots
created by the penetration of stones into the belt package) is reduced,
and the possibility of breaker edge separation is reduced. These
properties are believed to be due, at least in part, to improved
enveloping properties of the tread; the improved aged adhesion possible
between an organic cord or filament and rubber as compared to the aged
adhesion between rubber and steel; and the corrosion resistance of the
organic reinforcement as compared to the corrosion resistance of steel.
The invention is further illustrated with reference to the following
examples.
EXAMPLE 1
This example illustrates the impact resistance of is belt composites made
using 14 epi 6000 denier (6700 dTex) Hyten.RTM. monofilament reinforcement
in place of 8 epi steel cord reinforcement. The data shows that the energy
to rupture for the monofilament composite is down about 15 to 35% as
compared to the steel cord composite. Testing was carried out using 10
inch by six inch single layered, unidirectional composites where the
reinforcing cords are embedded in tread rubber. The control is a composite
made with 8 epi conventional steel cord reinforcement. The following data
illustrates the velocity of the plunger used in the test at impact, the
energy to rupture, and the breaking load.
TABLE 1
______________________________________
Impact Energy to
Veloc Rupture Break
Construction
(mph) (in-lb) Load (lb)
______________________________________
Control 4.00 124 583
3.75 128 602
3.63 129 528
3.56 120 575
3.50 121 602
3.43 Nodamage
6000d nylon
4.00 92 465
monofil 3.75 98 489
3.69 79 395
3.50 82 450
______________________________________
The data shows that the control absorbed approximately 25 to 45% more
energy than the nylon reinforced composite before rupture.
EXAMPLE 2
Tires size 11 R24.5 (Goodyear G188 Unisteel construction) were made in the
conventional manner except that the top (4th) belt was replaced by one ply
reinforced by 6,000 denier (6700 dtex) Hyten.RTM. monofilaments.
This example illustrates weight savings obtained by using nylon
monofilaments in a belt construction in an RMT tire where at least one of
the steel belts is replaced by an organic monofilament reinforced ply.
In the table below A represents 3x.22/9x.20+1 high tensile wire plies, and
B represents 3x.265/9x.245 high tensile wire plies. The weights of each
construction are provided in the numbers below the construction. All
weights below are treatment weights in pounds, reinforcement plus rubber.
TABLE 2
______________________________________
1st Hyten 2nd Hyten
Control build build
______________________________________
Belt 1 A (12) A (12) A (12)
2.30 2.30 2.30
Belt 2 B (12) (12) B (14)
5.61 5.61 6.05
Belt 3 B (12) B (12) B (14)
5.06 5.06 5.45
Belt 4 B (08) 6000d Hyten (14)
6000d Hyten (14)
3.32 1.60 1.60
Total 16.29 lbs 14.57 lbs 15.40 lbs
weight
weight -- 1.72 lbs 0.89 lbs
saving
______________________________________
Numbers in parentheses are ends per inch.
This example also illustrates laboratory test data for tires using a
monofilament reinforced top belt (#4 belt) as described in example 1 in
place of the conventional steel cord reinforced top belt. The first three
belts are conventional steel cord reinforced belts. Control 1 and nylon 1
denote the first build that was subjected only to laboratory testing.
Control 2 and nylon 2 denote the second build which was also used for road
testing, as reported in Example 3.
TABLE 3
______________________________________
Control 6000d control 6000d
1 nylon 1 2 nylon 2
______________________________________
Roll Resistance
100 103
Rating
Burst (psi)
410 385
Plunger energy
32134 33810 39610 51563
(in-lb)
120" smooth
16025 18419 14000 10691
wheel crown
durability (mi)
step load 15000 3 15000 4
durability (mi)
8000 1 finish
Heat Rise 30 mph 215 211
(F) Center, Shoul 203 203
______________________________________
In the table "finish" means no damage was seen when the test was stopped,
and the numbers in the right of the step load durability column denote the
number of tires.
The data in the table shows that physical properties of a tire made using a
nylon reinforced top belt are substantially equal to a conventionally
reinforced control tire.
EXAMPLE 3
Sixty tires were placed in a focus test group (30 control tires and 30
tires with a 6000 d (6700 dTex) nylon top belt from the second build
described in Example 2) to determine properties in actual use. The
properties observed are reported in the following table.
TABLE 4
______________________________________
6000d
Control
nylon
______________________________________
Rate of 100 99
Wear
Ranking
cut/chip/chunk
None 17% 10%
light 33% 34%
moderate 37% 42%
heavy 13% 14%
______________________________________
The table shows that properties of the tire made with the nylon reinforced
top belt, overall, are comparable to the control.
EXAMPLE 4
Tires size 315/80R22.5 (Goodyear G 391 Unisteel construction) were made in
the conventional manner except that tires were made wherein the top (4 th)
belt was replaced by one ply reinforced by 9,000 denier (10,000 dtex)
Hyten.RTM. monofilaments.
A total of 146 tires (96 control and 50 test) were placed in buses and
logging trucks in Sweden at the end of 1993.
The retreadable tires were retreaded in GW30 Goldwing contour from
Marangoni and were mounted on trucks.
Tires were photographed before and after the buffing operation.
Results
The following results should be viewed only as an indication of a trend
until all the remaining tires are returned and analyzed:
Bus Tires
All bus tires were retreadable with few or no buzz-outs per tire.
G391 tires were holding stones and there were some cases of stone
penetration.
There was no evidence that the nylon top breaker reduced stone
penetrations.
Logging Tires
G 250 tires with nylon top breaker were more retreadable (8 out of 8) than
those with steel cord top breaker (4 out of 9) However, this was mainly
due to breaker edge separations seen on the control tires.
Details
Size/Design: 315/80R22.5 G291/G391/G250/G386
Luxembourg,
negative crown
Service: Steer axle of inter-city buses
(G 291/G391)
Steer axle of logging trucks
(G 250/G386)
TABLE 5
______________________________________
BUSSES TRUCKS TOTAL
______________________________________
No of tires placed
74 75 146
No of tires
24 (32%) 38 (53%) 62 (42%)
inspected
______________________________________
TABLE 6
______________________________________
BUS 315/80R22.5 STEER
CONTROL HYTEN*
G291 G391 TOTAL
______________________________________
Tire placed 40 34 74
Tires inspected
17 7 24
Tires retreadable
17 7
% retreadable
100 100
______________________________________
TABLE 7
______________________________________
LOGGING TRUCKS 315/80R22.5 STEER
HYTEN*
CONTROL G250
G250 1 LAYER G386 TOTAL
______________________________________
Tires placed
18 18 36 72
Tires inspected
9 8 21 38 (53%)
Tires retreadable
4 8 4
% retreadable
44 100 19
______________________________________
*10,000 dtex (9000 denier) HYTEN, 12.5 epi
EXAMPLE 5
This example illustrates the results of running tires of the invention in
the sugar cane fields of Brazil where tires experience severe tread and
top breaker damage.
A fabric made from 6,700 dtex flat nylon 66 monofilament of Dupont (Hyten)
was dipped in Luxembourg and sent to Brazil for tire building. Test tires
were placed in sugar cane, mineral transport service and in intercity bus
service accounts together with control tires and with Michelin XZY tires.
Tires from sugar cane service were returned to Goodyear's Sao Paulo retread
shop and Goodyear Americana for retreading.
The retread operation was observed including buffing, buzz-out, and
cementing operations. All of the tires were inspected to determine the
actual number of buzz-out points on each tire.
Conclusions
Hyten tires are easier and quicker to process (buzz-out preparation) than
standard tires.
Among severely damaged tires, the hyten tires are more acceptable for
retreading compared to standard tires.
No specific debelting equipment is required for preparing hyten tires for
retreading.
Details
Tire Size/design: 10.00R20G386
Fleet: Usine da Barra Grande (Sugar cane service)
% On/Off Road: 50% on 50% off
Vehicles: MB2325 6.times.4
Constructions:
TABLE 8
______________________________________
Control HYTEN* Michelin
G386 G386 XZY
______________________________________
No of tires
40 40 40
replaced
No of tires
40 40 40
inspected
Breaker 4 B Hyten*
Km Removal
45555 41597 40234
Ave. Buzz-
85 43 24
outs/tire
No. Tires 11 12 10
with Tread
repairs
______________________________________
*6.700 dTex Hyten, 15 EPI
Tire size/design: 1100R22G386
Fleet: Usine da Barra (Sugar cane service)
% On/Off Road: 50% on/50% off
Vehicles: Scania 6.times.4
Constructions:
TABLE 9
______________________________________
Control HYTEN* Michelin
G386 G386 XZY
______________________________________
Breaker 4 B Hyten*
No of 8 3 4
vehicles
No of tires
80 30 40
placed
No. of 64 26 32
tires
inspected
Km removal
19724 19588 17923
Ave. buzz-
75 47 54
outs per
tire
No. tires 7 3 2
with tread
repairs
______________________________________
*6700 dTex Hyten, 15 epi
Interim Results/Observations
1. Hyten tires and control tires had similar worn tire appearance.
2. There was no evidence of reduced tire protection with hyten.
3. When cuts reached the hyten layer, damage stayed localized.
4. Hyten top breaker damage spots required only soft wire brushing.
5. Buzz-out processing was easier and faster with hyten tires than with the
control tires.
6. Excessive hyten top breaker damage could be easily removed by rasping (1
tire). No need for a special debelting device.
7. Tires with severely damaged steel cord top breaker were rejected from
processing. Similarly damaged hyten top breaker tires could be processed.
While the invention has been specifically illustrated and described, those
skilled in the art will recognize that the invention may be variously
modified and practiced without departing from the spirit of the invention.
The scope of the invention is limited only by the following claims.
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